You’re doing everything right.. eating better, moving your body, trying to sleep but still feel exhausted, moody, bloated, and like your body’s working against you? It might not be your willpower. But what is it then? It might be your vitamin D.
The so-called “sunshine vitamin” gets ignored until you finally test it and realise it’s way too low. And if you’re in your 40s and deep in perimenopause, this matters more than you think.
Lets discuss!
What Vitamin D Actually Does
There is more to Vitamin D than just about bone health. It acts more like a hormone and affects nearly every system in your body. It helps regulate:
- Immune health
- Mood and mental wellbeing
- Energy levels
- Hormones (including insulin and oestrogen)
- Muscle strength and joint health
- Sleep
- Inflammation
So when your vitamin D is low, it’s like trying to run a business with half your team missing. Nothing works the way it should.
Symptoms of Low Vitamin D
Here’s what I see all the time in women going through perimenopause:
- Fatigue, no matter how much you sleep
- Brain fog or trouble focusing
- Mood swings or ongoing low mood
- Muscle or joint pain, stiffness, or weakness
- Weight gain or plateau despite effort
- Getting sick often or feeling run down
- Sugar cravings and low motivation
- Dry skin, brittle nails, or hair thinning
- Poor sleep or waking up unrefreshed
Most women think these are just “normal” perimenopause symptoms but low vitamin D can make them a whole lot worse.
How It Affects Perimenopause
Perimenopause is already a hormonal juggling act. Oestrogen is dropping, progesterone is unstable, cortisol is often high, and sleep takes a walk.
Now add low vitamin D to the mix, and it becomes even harder to:
- Sleep through the night
- Recover from workouts
- Lose fat or maintain muscle
- Regulate mood and emotions
- Fight off illness or inflammation
It’s one more thing tipping the scales in the wrong direction.
What’s a Healthy Level?
This is where most people get misled.
- Most GPs look for levels above 50 nmol/L
- But optimal levels are more like 75 to 150 nmol/L
If your test says 41, you’re not just “a little low” , you’re functionally deficient. That’s not enough for your body to run properly, let alone thrive in midlife.
How to Fix It
- Get a blood test
Don’t guess. Ask your doctor or order a private test. - Supplement with Vitamin D3
Most women need between 1,000–4,000 IU daily, sometimes more short term. Always take it with food that contains fat to help absorption. - Be consistent
It can take 8–12 weeks to shift your levels and start feeling better. Stick with it. - Re-test
After 3 months, check again to make sure you’re in that 75–150 range.
So… If you’re doing all the right things but still feel off.. heavy, foggy, flat, sore and your vitamin D is low, this might be the missing piece.
Don’t let deficiency make an already tricky season of life harder than it needs to be. Get your levels up, and your energy, sleep, strength, and mood might finally start working with you instead of against you.
References:
Kaur, J., Khare, S., Sizar, O., & StatPearls Publishing. (2025). Vitamin D deficiency. In StatPearls. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK532266/
Bordelon, P., Ghetu, M. V., & Langan, R. C. (2009). Recognition and management of vitamin D deficiency. American Family Physician, 80(8), 841–846. https://pubmed.ncbi.nlm.nih.gov/19835345/
Grant, W. B., Wimalawansa, S. J., Pludowski, P., & Cheng, R. Z. (2025). Vitamin D: Evidence-based health benefits and recommendations for population guidelines. Nutrients, 17(2), 277. https://doi.org/10.3390/nu17020277
Głąbska, D., Kołota, A., Lachowicz, K., Skolmowska, D., Stachoń, M., & Guzek, D. (2021). The influence of vitamin D intake and status on mental health in children: A systematic review. Nutrients, 13(3), 952. https://doi.org/10.3390/nu13030952
